A monitoring appliance is an electronic device which will enable a person to perceive activity from a remote location: For example, a baby monitor is a known monitoring appliance that allows sound from a baby's room to be transmitted to another location; such as another room in a house.
Current monitoring appliances are made up of two parts, a low power FM radio receiver portion and a low power FM radio transmitter portion. The radio transmitter is placed in a room to be monitored and the corresponding radio receiver is kept in close proximity to the monitoring person. Some newer monitoring appliances contain a transmitter and a receiver in both of the two parts to allow bi-directional communication.
Using a monitoring appliance that is a low power FM radio transmitter and receiver pair has several drawbacks. The range of the FM transmitter used in monitoring appliances is short, typically less than 0.25 mile. Current monitoring appliances can not be checked from a distance using a telephone. For this reason the monitoring person is required to remain close to the room that is being monitored. This greatly limits the value of the monitoring devices.
Additionally, since monitoring appliances typically only allow the selection of one of a few frequencies the monitoring appliance can easily interfere with other monitoring appliances in the area. Also, neighbors can receive the transmissions from a monitoring appliance transmitter with a radio scanner to eavesdrop on anything that is said in the room containing the monitoring appliance transmitter. The receiver used in a radio scanner is usually more sensitive than the receiver in a monitoring appliance. The radio scanner can typically pick up the transmission from much greater distances than the monitoring appliance. Accordingly, it would be beneficial to provide a monitoring device that could place a call to remote telephones.